Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Patent
1994-10-21
1996-09-24
Turner, Samuel A.
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
356349, 356363, G01B 902
Patent
active
055595987
ABSTRACT:
A position detection apparatus for measuring the positions of a mask and a wafer, misalignment between the mask and the wafer, alignment of patterns on the wafer, or the like, includes a diffraction grating provided on the object, a light source for emitting light having a single frequency, an illuminating unit for projecting the light of the light source onto the diffraction grating, frequency modulators for performing frequency modulation of diffracted light beams from the diffraction grating, a combining unit for combining a first diffracted light beam subjected to the frequency modulation by one of the frequency modulaters, and a second diffracted light beam, having a diffraction order different from that of the first diffracted light beam, from the diffraction grating, photoelectric transducers for obtaining signals by detecting the light combined by the combining unit, and a signal processing system for detecting the position of the diffraction grating based on the phases of the signals.
REFERENCES:
patent: 4710026 (1987-12-01), Magome et al.
patent: 5369486 (1994-11-01), Matsumoto et al.
Canon Kabushiki Kaisha
Merlino Amanda
Turner Samuel A.
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